50 space terms for understanding the universe

NASA // Wikimedia Commons The National Aeronautics and Space Agency, or NASA, was founded on July 29, 1958, when President Dwight D. Eisenhower signed the National Aeronautics and Space Act, one year after the Soviets launched Sputnik 1, the world’s first artificial satellite. NASA was designed from the start to push the bounds of space exploration with research into aerospace and aeronautics as well as with a civilian space program. In honor of World Space Week, which takes place Oct. 4-10, Stacker compiled a list of key astronomy and astrophysics terms from a variety of authoritative science communication sources, including Crash Course: Astronomy, How Stuff Works, and International Comet Quarterly. As the agency unrelentingly forged a path toward astronomical discovery, NASA also invented a number of technologies that we use in our everyday lives. These include artificial limbs, LASIK surgery, improved water filtration, camera phones, freeze-dried foods, memory foam, LED lights, and even the Dust Buster. In fact, it was a NASA scientist who invented the Super Soaker squirt gun. Keep reading to learn the terms that are commonly used in this fascinating field. You may also like: Can you answer these real ‘Jeopardy!’ questions about space? #1. Aberration of light NASA Similar to how raindrops hit a moving car window as if from an angle, an aberration of light is the phenomenon where stars or other celestial bodies appear from Earth to be slightly off from their true position. This happens because of motion–specifically, the interaction of the Earth’s movement with the speed of light causes this confusing phenomenon. #2. Alpha Centauri Skatebiker // Wikimedia Commons Alpha Centauri is the name of the closest star system to earth. It comprises two main stars, Alpha Centauri A and Alpha Centauri B, as well as the closest of the three stars, Proxima Centauri. In 2016, astronomers found an Earth-sized planet orbiting Proxima Centauri, later named Proxima b. While this planet shows signs that life could exist, astronomers are still unsure how habitable it is.  #3. Andromeda Galaxy Adam Evans // Wikipedia Also known as M31, this galaxy is the closest to the Milky Way, where the Earth exists. Andromeda Galaxy has a similar structure to the Milky Way; it is spiral in shape and has a large density of stars, dust, and gas. Because of its proximity, it is the only galaxy that can be seen from Earth with the unaided eye, particularly on fall and winter nights.  #4. Asteroid NASA Asteroids are chunks of rock or metal that used to be parts of other small planets that have broken off due to a collision in space and now orbit the sun. The word asteroid means “star-like,” referring to their emission of light. Asteroids can be lumped into orbital groupings called families and form into an asteroid belt.  #5. Barycenter NASA Space Place // Wikimedia Commons A barycenter is the common center mass around which a solar system orbits. While it has become common knowledge that planets orbit stars, it is, in fact, the barycenter that both stars and planets orbit around. Our solar system’s barycenter is constantly changing position based on where each of the planets is in its orbit, ranging from being near the center of the sun to being just outside its surface.  #6. Big Bang NASA The Big Bang Theory is a model describing the origin of the universe. It explains how the universe expanded from a high-density, high-temperature state into the cosmos we see today. Although there are alternative theories, this is the most widely recognized theory of how the universe began. #7. Binary star NASA // Wikimedia Commons Made famous by Einstein’s theory of general relativity, a black hole is the small dense core remnant of a dead star. Since the density of this core is more than about three times more than the density of the sun, the strong force of gravity produces a black hole.    #9. Brown dwarf NASA Like the cosmic mystery its name evokes, dark energy is hard to define. The easiest way to think of it is a property of space that accounts for an expanding universe. The universe’s “empty space” may still have its own, dark energy. However, scientists are still trying to pin down the properties of this dark energy that makes up most of the universe. #14. Dark matter Smithsonian Institution // Wikimedia Commons Somewhat similar to dark energy, dark matter also covers a large chunk of the universe and remains quite mysterious to scientists. The main difference is that dark matter explains more about how groups of objects in the universe function together. Though scientists have a greater understanding of what dark matter isn’t than what it is, a leading theory posits dark matter is made from exotic particles like axions or Weakly Interacting Massive Particles (WIMPS).  #15. Doppler shift NASA/JPL-Caltech // Wikimedia Commons Also known to most as the Doppler effect, the Doppler shift explains the phenomenon of the change in frequency of a wave in relation to an observer. This can be observed when an ambulance drives past you and the volume of the siren doesn’t quite match with the proximity of the ambulance to you.  #16. Eclipse NASA An eclipse refers to one body in space moving into the shadow of another body. Eclipses can exist in two forms–solar and lunar–depending on the orbit of the Earth and moon. With a lunar eclipse, the moon moves behind the Earth. During a solar eclipse, the moon orbits between the Earth and the sun. #17. Equinox NASA During an equinox, Earth experiences an even 12 hours of daytime and 12 hours of nighttime. This occurs twice a year: The March equinox marks spring’s arrival in the Northern Hemisphere and Fall in the Southern Hemisphere. The September equinox ushers in the fall’s arrival in the north and spring in the south. #18. Escape velocity Alexander Mokletsov // Wikimedia Commons Escape velocity is the speed that an object needs in order to escape a planet or moon’s gravitational pull. For example, the escape velocity for a spaceship to leave the surface of Earth is about 25,000 miles per hour.    #19. Exoplanet NASA Named after astronomer Jan Oort whose theory about a cloud comprising a shell of icy objects existing beyond the Kuiper Belt, or the region that exists in our solar system beyond Neptune, could be responsible for the long-term comets visible from Earth (like Halley’s). The cloud is theorized to comprise the remains of disc materials of planets and the sun. #35. Orbit NASA // Wikimedia Commons In short, an orbit is the gravitationally curved trajectory of an object in space. In other words, an orbit is the circular motion in which objects in space travel due to gravity’s pull. For example, the moon orbits around the Earth and the Earth orbits around the sun in a circular motion. An object that orbits another is called its satellite. #36. Parallax NASA Quasars are large distant objects in space that are powered by large, powerful black holes. They tend to shine so brightly that their light eclipses the old galaxies that they exist within. They are capable of emitting thousands of times more energy than the Milky Way emits. #38. Red giant NASA A red giant is a star that is reaching its final days and approaching death. If a star has turned into a red giant, the star is in the last states of its stellar evolution and expands. Our own sun will eventually expand and turn into a red giant–but not for a few billion years.  #39. Red shift